feat: groupes de travail (P5)

Ajoute la notion de groupe — collection nommée de repos (membership légère
persistée, many-to-many) — pour piloter plusieurs repos en simultané :

- DB : migration #5 (tables groups + group_repos, FK ON DELETE CASCADE).
- GroupManager (synchrone, EventEmitter) + routes REST /api/v1/groups ;
  ne persiste que la membership, worktrees/sessions filtrés par repoId côté client.
- Protocole : GroupSummary, DTOs, topic WS « groups », events group_update/removed
  (additifs, PROTOCOL_VERSION inchangé).
- Web : store groups, GroupsListView, GroupView (réutilise RepoSection),
  grille multi-terminaux (TerminalGrid/TerminalCell), action « feature cross-repo »
  (orchestration client, tolérante aux échecs partiels), routes + i18n EN/FR.
- Tests : group-manager.test.ts + extension protocol.test.ts ; acceptance-p5.mjs.

packages/web/src/lib/api.ts

@@ -34,5 +34,6 @@ async function request<T>(path: string, method: string, body?: unknown): Promise
 export const api = {
   get: <T>(path: string): Promise<T> => request<T>(path, 'GET'),
   post: <T>(path: string, body?: unknown): Promise<T> => request<T>(path, 'POST', body),
+  patch: <T>(path: string, body?: unknown): Promise<T> => request<T>(path, 'PATCH', body),
   delete: <T>(path: string): Promise<T> => request<T>(path, 'DELETE'),
 };

packages/web/src/lib/ws-client.ts

@@ -28,6 +28,7 @@ export interface TerminalSink {
 
 export type SessionEvent = Extract<ServerMessage, { type: 'session_update' | 'session_exit' }>;
 export type WorktreeEvent = Extract<ServerMessage, { type: 'repo_update' | 'repo_removed' | 'worktree_update' | 'worktree_removed' }>;
+export type GroupEvent = Extract<ServerMessage, { type: 'group_update' | 'group_removed' }>;
 
 export interface AttachOptions {
   sessionId: string;
@@ -116,6 +117,7 @@ export class WsClient {
   private awaitingAttached: Attachment[] = [];
   private readonly sessionListeners = new Set<(e: SessionEvent) => void>();
   private readonly worktreeListeners = new Set<(e: WorktreeEvent) => void>();
+  private readonly groupListeners = new Set<(e: GroupEvent) => void>();
 
   connect(): void {
     this.stopped = false;
@@ -156,10 +158,11 @@ export class WsClient {
   }
 
   /** topics actifs = union des abonnements courants (une seule connexion partagée). */
-  private activeTopics(): Array<'sessions' | 'worktrees'> {
-    const t: Array<'sessions' | 'worktrees'> = [];
+  private activeTopics(): Array<'sessions' | 'worktrees' | 'groups'> {
+    const t: Array<'sessions' | 'worktrees' | 'groups'> = [];
     if (this.sessionListeners.size > 0) t.push('sessions');
     if (this.worktreeListeners.size > 0) t.push('worktrees');
+    if (this.groupListeners.size > 0) t.push('groups');
     return t;
   }
 
@@ -187,6 +190,16 @@ export class WsClient {
     };
   }
 
+  subscribeGroups(listener: (e: GroupEvent) => void): () => void {
+    this.groupListeners.add(listener);
+    this.connect();
+    this.sendSub();
+    return () => {
+      this.groupListeners.delete(listener);
+      this.sendSub();
+    };
+  }
+
   sendControl(msg: ClientMessage): void {
     if (!this.ready || this.socket?.readyState !== WebSocket.OPEN) return;
     this.socket.send(JSON.stringify(msg));
@@ -380,6 +393,11 @@ export class WsClient {
         for (const cb of this.worktreeListeners) cb(msg);
         return;
       }
+      case 'group_update':
+      case 'group_removed': {
+        for (const cb of this.groupListeners) cb(msg);
+        return;
+      }
       case 'error': {
         if (msg.channel !== undefined) {
           console.warn(`[ws] channel ${msg.channel}: ${msg.code} — ${msg.message}`);